Field of the Invention
The present invention relates to image processing techniques for performing rotation processing and region specification processing on a three-dimensional medical image in such a manner that the two kinds of processing are switched with each other. Particularly, the present invention relates to an image processing technique for repeating rotation of a displayed three-dimensional medical image and deletion of an unneeded part of the three-dimensional medical image, and which is appropriate for extracting only a desired organ from the three-dimensional medical image.
Description of the Related Art
In recent years, an advance of image processing techniques made it possible to generate projection images by projecting a three-dimensional medical image from various angles by using various image generation methods, such as volume rendering and surface rendering. The generated projection images are displayed on a display screen, as a moved image, an enlarged image, a rotated image or the like of the three-dimensional medical image, by a user's operation of a mouse or the like on the display screen. Such images can aid three-dimensional recognition and understanding of the three-dimensional medical image.
Conventionally, rotation of a three-dimensional medical image to various directions and deletion of an unneeded region in the three-dimensional medical image by specifying the unneeded region are repeated in general by a manual operation of a mouse or a keyboard by a user who is a radiographer or the like. The processing is repeated may times to extract, based on the purpose of diagnosis, a desired region from the three-dimensional medical image. The processing is repeated until only the desired region is included in the three-dimensional medical image, and the extracted region is displayed. Therefore, there is a demand for simplifying, as much as possible, the manual operation by the user to perform rotation of a three-dimensional image to various direction and deletion of an unneeded region in the three-dimensional medical image.
For example, a method for switching region specification processing and rotation processing with each other has been proposed. In the method, the region specification processing is assigned to a drag operation by the left button of a mouse, and the rotation processing is assigned to a drag operation by the left button of the mouse with a shift button on a keyboard pressed. In this method, switching of processing is simplified by combining the single operation, i.e., the drag operation by the left button of the mouse, with presence or non-presence of an operation of pressing a shift key on a keyboard.
Further, Japanese Unexamined Patent Publication No. 2005-296156 (Patent Document 1) discloses an image processing method in which different kinds of processing function are assigned to plural regions a, b, c . . . , respectively. The plural regions a, b, c . . . are obtained by dividing, in a predetermined division pattern, a display screen for displaying an image obtained by imaging. In the method, specification of a desired region by a pointing device is received, and a processing function assigned to the specified region is executed by an operation of the pointing device.
Meanwhile, in situations in which a computer terminal for image processing is used to display and to edit a three-dimensional medical image obtained by imaging, there is a demand for performing various operations by using only a mouse without using a keyboard. However, the method of switching the region specification processing and the rotation processing with each other by combining the single operation of the drag operation by the left button of the mouse with presence or non-presence of an operation of pressing a shift button on the keyboard does not satisfy the user's demand.
Further, in the method disclosed in Patent Document 1, it is impossible to recognize, by intuition, correspondence between plural regions and functions assigned to the plural regions. Therefore, there has been a problem that the method is hard to use especially for inexperienced users. Further, in processing, such as region specification processing, an arbitrary part of a three-dimensional image needs to be freely specified as needed. In such processing, if functions are assigned to regions divided as illustrated in FIGS. 2 and 3 of Patent Document 1, each of the areas of the regions to which functions are assigned is too small. Therefore, when a desired part of the three-dimensional medical image is not included in a region to which region specification processing is assigned, extra work, such as parallel movement of the three-dimensional medical image or enlargement/reduction of the three-dimensional medical image, is necessary to make a region to which region specification processing is assigned include the desired part of the three-dimensional medical image. Hence, it is impossible to sufficiently reduce the user's work in switching plural kinds of processing with each other.